1. Field of the Invention and Contract Statement
The invention relates to a system for in-situ remediation of contaminated ground water.
2. Discussion of Background and Prior Art
Contaminated groundwater poses a serious health problem when used as a source of water for drinking or for growing crops and vegetation. Additionally, the cost of containing and decontaminating groundwater can be high.
The most direct methods of removing contamination from groundwater and soils are by excavating contaminated subsurface materials, such as soils, sediments, fractured rock, and the like, and by pumping contaminated water from subsurface materials to the surface of the earth for treatment. Both excavating and pumping, although direct methods of dealing with contaminated groundwater, are expensive.
Recently, methods for drilling horizontal wells have been developed. In "Radial Wells and Hazardous Waste Sites", Wade Dickinson, R. Wayne Dickinson and Peter A. Mote, describe a method for drilling of horizontal wells in detail and also note the potential use of horizontal wells for remediation of contaminated groundwater. Wells placed into the contaminated area may be used for extraction of contaminated groundwater or to inject various treatment substances.
Related U.S. Pat. Nos. 4,593,760 and 4,660,639 describe a method by Visser, et al., for removing volatile contaminants from the upper, unsaturated or "vadose" zone of the groundwater. Wells sunk vertically into the vadose zone may have a casing consisting of two sections, an upper unperforated region and a lower perforated region. Volatile contaminants in the vadose zone enter the perforated casing and are pumped past the unperforated casing to the earth's surface for treatment.
The prior art generally comprises passive rather than active systems for collection of contamination and systems operating only in the vadose zone rather than systems operating in both the saturated and vadose zones. Although injection of treatment substances for in-situ treatment has been conceptualized by the prior art, the effectiveness of treatment through injection is unknown without substantial post-injection sampling.
None of the prior art remediation methods comprises the use of horizontal wells for saturated zone injection of fluids that volatilize contaminants and extraction of those volatilized contaminants to remediate contaminated groundwater.